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This is a small collection of useful Pandoc filters(in Haskell) and explanations.

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Below is the presentation in markdown_github format. To view as slide show by use of rawgithub.com here.

Swiss Arm Knife Converstion Tool

  • Pandoc is can be used to convert between a number of markdown and markup file formats

    Input formats:  docbook, haddock, html, json, latex, markdown,
                    markdown_github, markdown_mmd,
                    markdown_phpextra, markdown_strict, mediawiki,
                    native, opml, org, rst, textile
    Output formats: asciidoc, beamer, context, docbook, docx,
                    dzslides, epub, epub3, fb2, html, html5, icml,
                    json, latex, man, markdown, markdown_github,
                    markdown_mmd, markdown_phpextra,
                    markdown_strict, mediawiki, native, odt,
                    opendocument, opml, org, pdf*, plain, revealjs,
                    rst, rtf, s5, slideous, slidy, texinfo, textile
                    [*for pdf output, use latex or beamer and -o FILENAME.pdf]
    

Focus

  • markdown
  • html
  • A touch of json
  • Easy of scripting
  • Pandoc was used to make these slides

markdown to html

## hi

This is text and [this is a link.](http://www.example.com)
<h2 id="hi">hi</h2>
<p>This is text and <a href="http://www.example.com">this is a link.</a></p>

When rendered:

hi

This is text and this is a link.

More

## This is a list

* item one
* item two
<h2 id="this-is-a-list">This is a list</h2>
<ul>
<li>item one</li>
<li>item two</li>
</ul>

rendered:

This is a list

  • item one
  • item two

Easy of use

  • Less verbose then html, json, man, opml, epub, etc.
    • Write in what you know convert to what you do not.
    • Still recoment markdown ubiquity.
  • Flexible and scriptible
  • Who has the time to learn all of these formats? Epessially if you want content in multiple formats.

Who has the time? markdown -> html

## This is a list

* item one
* item two
<h2 id="this-is-a-list">This is a list</h2>
<ul>
<li>item one</li>
<li>item two</li>
</ul>

Who has the time? markdown -> asciidoc

## This is a list

* item one
* item two
[[this-is-a-list]]
This is a list
~~~~~~~~~~~~~~

* item one
* item two

Who has the time? markdown -> docbook

## This is a list

* item one
* item two
<sect1 id="this-is-a-list">
  <title>This is a list</title>
  <itemizedlist spacing="compact">
    <listitem>
      <para>
        item one
      </para>
    </listitem>
    <listitem>
      <para>
        item two
      </para>
    </listitem>
  </itemizedlist>
</sect1>

Who has the time? markdown -> latex

## This is a list

* item one [link](http://www.example.com]
* item two
\subsection{This is a list}\label{this-is-a-list}

\begin{itemize}
\itemsep1pt\parskip0pt\parsep0pt
\item
  item one {[}link{]}(http://www.example.com{]}
\item
  item two
\end{itemize}

Who has the time? markdown -> json

## This is a list

* item one
* item two
[{"unMeta":{}},[{"t":"Header","c":[2,["this-is-a-list",[],[]],[{"t":"Str","c":"This"},{"t":"Space","c":[]},{"t":"Str","c":"is"},{"t":"Space","c":[]},{"t":"Str","c":"a"},{"t":"Space","c":[]},{"t":"Str","c":"list"}]]},{"t":"BulletList","c":[[{"t":"Plain","c":[{"t":"Str","c":"item"},{"t":"Space","c":[]},{"t":"Str","c":"one"}]}],[{"t":"Plain","c":[{"t":"Str","c":"item"},{"t":"Space","c":[]},{"t":"Str","c":"two"}]}]]}]]

This can represent all of pandoc's internal AST.

Who has the time? markdown -> etc

Output formats: asciidoc, beamer, context, docbook, docx,
                dzslides, epub, epub3, fb2, html, html5, icml,
                json, latex, man, markdown, markdown_github,
                markdown_mmd, markdown_phpextra,
                markdown_strict, mediawiki, native, odt,
                opendocument, opml, org, pdf*, plain, revealjs,
                rst, rtf, s5, slideous, slidy, texinfo, textile
                [*for pdf output, use latex or beamer and -o FILENAME.pdf]

Scriptablity

Since it is easy to out the internal AST it is simple to filter and edit the AST and send it along to other formats.

In fact that is what I have been doing for all of my little converstion examples. I would have been too lazy to copy and paste all of the converstions you have seen so far.

So instead I made a small haskell script to access and filter pandoc AST with command line commands.

Scriptablity CLI

 ```{ cmdBlock="pandoc -t html5" inClasses="markdown" outClasses="html5"}
 ## This is a h2 header

becomes:

``` {.markdown}
## This is a h2 header
<h2 id="this-is-a-h2-header">This is a h2 header</h2>

Scriptablity CLI - ls

 ```{ showCmdBlock="ls -l" outClasses="bashOut"}
 ## This is a h2 header

becomes:

``` {.bash}
$ ls -l
total 2548
-rw-r--r-- 1 pjw users   24725 Jun 11 01:52 20140608-Science-Sunday.html
-rw-r--r-- 1 pjw users    6106 Jun 11 14:15 20140608-Science-Sunday.md
-rw-r--r-- 1 pjw users    3080 Jun 11 14:20 diaExample.svg
-rw-r--r-- 1 pjw users   61550 Jun 11 14:19 dotExample.png
-rwxr-xr-x 1 pjw users    1241 Jun 11 14:19 pandocCmdFilter.hs
-rw-r--r-- 1 pjw users    8926 Jun 11 14:20 README.md
-rwxr-xr-x 1 pjw users 2411446 Jun 11 14:20 tmp
-rw-r--r-- 1 pjw users     681 Jun 11 14:19 tmp.dot
-rw-r--r-- 1 pjw users   17809 Jun 11 14:20 tmp.hi
-rw-r--r-- 1 pjw users     380 Jun 11 14:19 tmp.hs
-rw-r--r-- 1 pjw users   41544 Jun 11 14:20 tmp.o

Filters

  • Pattern match on datatype
  • Then transform and preform IO actions to create a new Block datatype.

Command Line Filter

To inport a file with highlighting:

 ```{ cmdBlock="cat pandocCmdFilter.hs" outClasses="haskell"}

``` {.haskell}
#!/usr/bin/env runhaskell
-- behead2.hs
import Text.Pandoc.JSON

import System.Process

import Data.Monoid
import Data.List (find)

main :: IO ()
main = toJSONFilter handleCmds

handleCmds :: Block -> IO Block
handleCmds (CodeBlock (ident, [] , (("showCmdBlock",cmd0):attrs)) code) = do
    cmdBlock <- handleCmds $ CodeBlock (ident, [], (("cmdBlock",cmd0):attrs)) code
    return $ Div ("", ["groupCodeBlock"], [])
                 [ CodeBlock (ident, ["bash"], []) $ "$ " <> cmd0
                 , cmdBlock
                 ]
handleCmds (CodeBlock (ident, [] , (("cmdBlock",cmd0):attrs)) code) = do
    let (cmd:args) = words cmd0
    let outClasses =
              words
            . maybe [] snd
            . find ((== "outClasses") . fst)
            $ attrs
    let inClasses =
              words
            . maybe [] snd
            . find ((== "inClasses") . fst)
            $ attrs
    let inputBlock =
            if null code
            then Null
            else CodeBlock (ident, inClasses, []) code
    result <- readProcess cmd args code
    return $ Div ("", ["groupCodeBlock"], [])
                 [ inputBlock
                 , CodeBlock (ident, outClasses, []) result
                 ]
handleCmds x = return x

GraphViz - Inline dot files

test

Inline Diagrams Code

{-# LANGUAGE NoMonomorphismRestriction #-}
import Diagrams.Prelude
import Diagrams.TwoD
import Diagrams.Backend.SVG
import Data.List

example = hrule (2 * sum sizes) === circles # centerX
  where circles = hcat . map alignT . zipWith scale sizes
                $ repeat (circle 1)
        sizes   = [2,5,4,7,1,3]

main = renderSVG "diaExample.svg" (Width 500)  (example # lw 0.2)

test

Easy of use + Scriptablity

  • Pleanty of examples of scriptin Pandoc in:
    • Haskell
    • Python
    • Perl
    • others
    • If you can handle JSON you can script Pandoc
  • Go forth and create and customize.

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